Irrigation drip emitters are commonly used in irrigation systems to convert fluid flowing through a supply tube or drip line at a relatively high flow rate to a relatively low flow rate at the outlet of each emitter. Such emitters are typically used in landscaping (both residential and commercial) to water and/or treat (e.g., fertilize) trees, shrubs, flowers, grass and other vegetation, and in agricultural applications to water and/or treat crops. Typically, multiple drip emitters are positioned on the inside or outside of a water supply line or tube at predetermined intervals to distribute water and/or other fluids at precise points to surrounding land and vegetation. The emitter normally includes a pressure reducing passageway, such as a zigzag labyrinth or passage, which reduces high pressure fluid entering the drip emitter into relatively low pressure fluid exiting the drip emitter. Generally, such drip emitters are formed in one of three common manners: (1) separate structures connected to a supply tube either internally (i.e., in-line emitters) or externally (i.e., on-line emitters or branch emitters); (2) drip strips or tape either connected to an inner surface of a supply tube or in-between ends of a material to form a generally round supply tube or conduit; and (3) stamped into a surface of a material that is then folded over upon itself or that overlaps itself to form a drip line with an enclosed emitter.
With respect to the first type of common drip emitter, the emitter is constructed of a separate housing that is attached to the drip line. The housing is normally a multi-piece structure that when assembled defines the pressure reducing flow path that the fluid travels through to reduce its pressure. Some examples of in-line emitters that are bonded to an inner surface of the supply line or tube are illustrated in U.S. Pat. No. 7,648,085 issued Jan. 19, 2010 and U.S. Patent Application Publication No. 2010/0282873, published Nov. 11, 2010, and some examples of on-line emitters which are connected to an exterior surface of the supply line or tube (usually by way of puncture via a barbed end) are illustrated in U.S. Pat. No. 5,820,029 issued Oct. 13, 1998. Some advantages to in-line emitters are that the emitter units are less susceptible to being knocked loose from the fluid carrying conduit and the conduit can be buried underground if desired (i.e., subsurface emitters) which further makes it difficult for the emitter to be inadvertently damaged (e.g., by way of being hit or kicked by a person, hit by a lawnmower or trimmer, etc.).
With respect to the second type of emitter, (i.e., drip strips or tape), the emitter is typically formed at predetermined intervals along a long stretch of material which is either bonded to the inner surface of the supply line or connected between ends of a material to form a generally round conduit or supply line with the strip or tape running the longitudinal length of the conduit. Some examples of drip strips or tape type emitters are illustrated in U.S. Pat. No. 4,726,520 issued Feb. 23, 1988.
With respect to the third type of emitter, (i.e., folded or overlapping tube emitters), the emitter is typically formed by stamping a pressure reducing flow path on one surface of a tube making material at or near an end thereof which is then folded back over on itself or which is wrapped such that the opposite end of the tube making material overlaps the end with the stamped flow path to form an enclosed pressure-reducing passageway. Some examples of folded or overlapping tube emitters are illustrated in U.S. Pat. No. 4,726,520 issued Feb. 23, 1988, and International Patent Application Publication No. WO 00/01219 published Jan. 13, 2000.
In addition, many if not all of the above mentioned emitters can be manufactured with a pressure compensating mechanism that allows the emitters to adjust or compensate for fluctuations in the fluid pressure within the supply line. For example, some of the above emitters include separate elastomeric diaphragms which are positioned adjacent the pressure reducing passageway and help reduce the cross-section of the passageway when an increase in supply line fluid pressure occurs and increase the cross-section of the passageway when a decrease in the supply line fluid pressure occurs.
While each of these forms of emitters has its own advantage, they each require either multiple pieces to be assembled, aligned and carefully bonded to the supply line or intricate stamping and folding or overlapping to be performed in order to manufacture the emitter and ensure that the emitter operates as desired. Thus, these emitters often require more time and care to assemble which needlessly can slow down the production of the drip line and/or emitter and can increase the cost of the drip line and/or emitter as well. Thus, there is a need for a simpler emitter construction that can be manufactured faster and using fewer parts and without wasting as much time, energy and materials related to aligning and assembling multiple parts of the emitter and/or folding or overlapping materials.
In addition, some of the above-mentioned emitters introduce structures (sometimes even the entire emitter body) into the main lumen of the supply line or tube which can cause turbulence and result in later emitters or emitters further downstream not working as well or efficiently as earlier emitters or upstream emitters. For example, in some of the non-pressure compensated emitters the introduction of too much turbulence from emitter structures located upstream can reduce the pressure of the fluid further downstream and result in the downstream emitters trickling water at a different flow rate than upstream emitters. This is not normally desirable as in most applications it would be desirable that the emitters of the drip line saturate their respective surrounding area at a common flow rate rather than having one portion of the drip line saturate one area more than another portion of the drip line saturates another area.
In other in-line emitters, large cylindrical structures are used which interfere with the flow of the fluid traveling through the drip line or tube and introduce more turbulence to the fluid or system due to the fact they cover and extend inward from the entire inner surface of the drip line or tube. The increased mass of the cylindrical unit and the fact it extends about the entire inner surface of the drip line or tube also increases the likelihood that the emitter will get clogged with grit or other particulates (which are more typically present at the wall portion of the tube or line than in the middle of the tube or line) and/or that the emitter itself will form a surface upon which grit or particulates can build-up on inside the drip line and slow the flow of fluid through the drip line or reduce the efficiency of the fluid flowing therethrough. Thus, there is also a need to reduce the size of in-line emitters and improve the efficiency of the systems within which these items are mounted.
Thus, there is a need for a new drip line and/or emitter that does not introduce structures into the central or main lumen of the supply line or drip line, that does not introduce turbulence into the system and/or that does not provide a surface for grit to build-up on, all of which could affect the operation of the drip line or emitters and, particularly, negatively affect the operation of downstream emitters. Providing such an emitter with a pressure compensating feature would also be desirable.
As mentioned above, some emitters can be positioned within the supply line or drip line so that the supply line can be buried underground (i.e., subsurface applications). In addition to the advantages of in-line emitters, subsurface drip emitters provide numerous advantages over drip emitters located and installed above ground. First, they limit water loss due to runoff and evaporation and thereby provide significant savings in water consumption. Water may also be used more economically by directing it at precise locations of the root systems of plants or other desired subsurface locations.
Second, subsurface drip emitters provide convenience. They allow the user to irrigate the surrounding terrain at any time of day or night without restriction. For example, such emitters may be used to water park or school grounds at any desired time. Drip emitters located above ground, on the other hand, may be undesirable at parks and school grounds during daytime hours when children or other individuals are present.
Third, subsurface emitters are not easily vandalized, given their installation in a relatively inaccessible location, i.e., underground. Thus, use of such subsurface emitters results in reduced costs associated with replacing vandalized equipment and with monitoring for the occurrence of such vandalism. For instance, use of subsurface emitters may lessen the costs associated with maintenance of publicly accessible areas, such as parks, school grounds, and landscaping around commercial buildings and parking lots.
Fourth, the use of subsurface drip emitters can prevent the distribution of water to undesired terrain, such as roadways and walkways. More specifically, the use of subsurface drip emitters prevents undesirable “overspray.” In contrast, above-ground emitters often generate overspray that disturbs vehicles and/or pedestrians. The above-identified advantages are only illustrative; other advantages exist in connection with the use of subsurface drip emitters.
One problem associated with using conventional emitters in subsurface applications is that they are prone to obstruction due to grit build-up and root growth. With respect to the latter, conventional emitters typically have difficulty in being used in at least sub-surface applications due to root obstruction that occurs from plants or vegetation growing toward the emitter creating an obstruction to the normal flow of fluid through the emitter. In the past, chemicals have been devised for use with sub-surface irrigation equipment to inhibit such root growth/interference, but these chemicals are either expensive to use or damaging to other materials used in the irrigation system (e.g., tubing, couplings, valves, the emitter itself, etc.).
Although some advantages of subsurface emitters are described above, it would be desirable to provide an improved drip emitter design that can be used in both subsurface and above ground applications that provides relatively constant fluid output from each of the emitters in the irrigation system without the problems associated with conventional emitters (e.g., negative effects of turbulence and grit build-up associated with emitters that project into the central or main lumen of the supply line, multi-part construction requiring alignment and assembly, complex folding/overlaying, root obstruction, etc.).
Accordingly, it has been determined that the need exists for an improved emitter construction and/or drip line and methods relating to same which overcomes the aforementioned limitations and which further provides capabilities, features and functions, not available in current drip lines or emitters and methods.
Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.